Many coastal locations in the world have the potential for tidal power generation but lack the ability to provide firm power. Present tidal power production designs and systems typically lack the infrastructure or adequate efficiency to store and release a practical amount of energy during slack tide. For instance, Graham Island of Haida Gwaii is presently without an adequate firm source of “green” energy to replace the diesel generators now in use there. Graham Island has the potential for both wind and tidal power according to S. Hart, 2008, “Haida Gwaii/Queen Charlotte Islands Demonstration Tidal Power Plant Feasibility Study. A Hatch Energy report for British Columbia Ministry of Energy, Mines and Petroleum Resources.” However, both sources provide intermittent energy production in the absence of storage.
Various systems have been proposed in the art that use water movement as a source of energy and fluid pumped to an elevated reservoir to store the energy prior to using the fluid to drive a turbine for generating electricity. For instance, published US application US2007/258771 discloses a simple way using a class #2 simple lever machine principal to harvest and transport energy from the bottom of an ocean or lake from the action of water waves beyond the shore and up on land. The fulcrum for this lever is an anchor on the seafloor, at the opposite end of this lever, the force, or energy, is an attached water container that rises and falls with water wave action. A water pump anchored to the seafloor and reaching the underside of the water container receives the energy and pumps water continually and harmoniously with the vertical movements of this water container to shore and into a fresh water reservoir. After the water has lost its energy to do work from its loss of elevation below the reservoir it can be recycled back to the water pump. This application will show the water from the reservoir to be used in the generation of electricity and either recycled back to the water pump, or wasted after use, and a continual supply of fresh water from another source is available for use.
However, the pumps suggested for use in hydroelectric power systems like the preceding are typically limited in their ability to efficiently adjust for the variable, intermittent energy available from tides and/or waves. Pumps considered in the prior art may be unable to both provide sufficient output pressure to pump fluid to the reservoir at times of weak energy supply (e.g. slack tide), while also taking full advantage of the available energy at times of strong energy supply (e.g. peak tide flow rate).
Axial piston pumps using designs and configurations based on rotating piston clusters and fixed (non-rotating) swash plates have been used for decades in diverse high rpm industrial applications (e.g. transmissions). Generally, such pumps are fixed displacement types in which the angle of the swash plates with respect to the rotating piston clusters is fixed. However, axial piston pumps with variable displacement are also known in the art in which the angle of the swash plates in the aforementioned designs can be adjusted with respect to the rotating piston clusters during use. Further still, fixed displacement axial piston pumps with fixed piston clusters and swash plates that rotate at a fixed angle to the shaft are also known in the art.
There remains a continuing need for more efficient hydroelectric power systems and pumps therefor to store and release energy from water sources flowing at considerably varied speeds. The present invention addresses this need while additionally providing other benefits as disclosed herein.